1. Field of the Invention
The present invention relates to chemical disinfection and, more particularly, to an improved biocidal aldehyde composition particularly suited for secondary oil and gas recovery and/or medical surface sterilization in the form of an immersion solution, spray or wipe.
2. Description of the Background
The purpose of disinfection is to reduce microbial contamination to an innocuous level. There is a widespread need for effective antimicrobials across diverse industries, including for oil and gas recovery (for treatment, penetration and removal of biofilm), and for disinfection of surfaces in the form of an immersion solution, spray, or pre-moistened cleaning wipette, etc. For oil and gas, microorganism growth leads to biofilm formation, which contributes to corrosion, contamination of oil and gas, and degradation of drilling muds and blockage. There are a few existing commercial biocides that purport to solve the need. For surface disinfection in the medical field, the goal is true “sterilization”, which per FDA requirement requires inactivation of 100% of all the living pathogens, not merely inactivation of some. A biocide that demonstrates only 90% cidal effectiveness is essentially ineffective due to the substantial bacterial rebound effect the remaining 10% will cause.
Chemical disinfection in the areas of health care, water treatment, oil/gas biocides have need to move into new areas of low environmental impacts while still maintaining an effective tidal component at the lowest concentrations possible. Unfortunately advances in microbial disinfection have been negligible. Singular chemistries have been the prevailing approach along with additive concepts. However these approaches tend not to provide the required effectiveness without increasing toxicity and environmental issues. New directions, and new “synergistic” biocidal combinations are necessary to meet new problems and the new environmental regulations.
For years developmental chemistries did not make proper use of chemical kinetics or cellular micro components. Solutions are either bacteriostatic or bactericidal depending on concentration, and a single-faceted targeted attack is only partially effective. However, the present inventor recognizes that a multi-faceted attack on the cell wall, membrane and cellular components of bacteria can be significantly more effective than a targeted attack. What is needed is a synergistic compound with superior activity against bacteria while maintaining low toxic effects. With a synergistic formulation, the cidal effects are enhanced at low toxic concentrations and low environmental effect.
The key to achieving this difficult combination effect is to develop a “synergistic” compound of two existing biocides with accelerant expedients that will exhibit this singular characteristic.
The standard biocide used in health care and oil/gas water treatment is Glutaraldeyhde. However, Glutaraldehyde requires time and temperature control (residence time of 45-90 minutes for disinfection, and controlled temperature of from 20 C to 25-30 C). Glutaraldehyde requires activation and dating to make it useful. Thus, proper usage entails a three step procedure and meticulous record-keeping regarding date of activation. It is shown by Flow Cytometry that Glutaraldehyde alone (Davison et al, Antimicrob Agents & Chemther, 2010) has little or no penetration of biofilm where the important sessile organism reside. The Glut requires the penetrating ability of benzalkoniom chloride (BAK). This was determined using the MetaMorph image analysis program. Biofilms treated with Glut retained intracellular fluorescence because the Glut did not permeabilize the cell membrane. The Glut will kill rapidly the planktonic but not biofilm protected organisms.
What is needed is a simple and improved one-step formulation that uses Glutaraldehyde in combination with other constituents for more effective disinfection/sterilization in industrial/commercial uses such as oil and gas recovery and medical surface sterilization. However, biocide combinations may be too additive or not enough to be effective. The constituents alone seldom achieve the desired effect because the requisite amounts and/or concentrations are too high. Biocides exhibit a biocidal “window” of peak effect. As their concentrations increase beyond this “window” their effectiveness degrades, and they also exceed low toxicity requirements.
Synergism is the superior and correct method to develop new formulations rather than additive. This is easily described by the typical Langmuir pattern, (L-shaped) which is indicative of a situation where as sites of drug uptake become filled, additional drug will find it difficult to find a vacant site. This illustrates the fallacy of someone believing that increasing drug concentration or volume for more effect. This is the “dose/concentration reaction.” The curve representing the dose/response is diphasic, where in one case nothing more happens or in the second case, over concentration, it reverses itself thru membrane coagulation. It has also been found that sublethal concentrations actually may stimulate growth or resistance. There is a “window of effect.” Another drug pattern uptake is called the “high affinity H pattern” where the drug molecule has a strong affinity for the cell which is ideal. Most antibacterial drugs fall between L and H patterns, the present invention being closer to the H pattern.
The present invention provides a combination approach that uses two compounds with two different mechanisms of action to create a neoteric approach to the twin effects of cidal effectiveness and biofilm reduction. The present invention uses a surfactant BAK in combination with Glutaraldehyde and other constituents for more effective disinfection/sterilization. The combination is synergistic, rather than additive, which increases the permeability effect. This effect enables the “multiple-hit” effect on the bacterial cell so the cidal effects of the acidic Glutaraldehyde are improved, without activator/buffer, to a superior effect. This can be expressed mathematically thru the “probabilistic effect” in a given time “t” if inactivating a site within the cell containing “n” such sites necessary for viability is P={1−exp(−kt)}n where n=intercept hits to bring death to the cell. The present formulation falls between L and H but is closer to H indicating superior uptake and therefore enabling it to be more effective as the cidal tests support.
A posteriori assessments of the formulation cannot predict future results. In light of the extremely unpredictable nature of combination biocides, results are not additive because reactions are not clearly defined until test results are provided. Theory must be validated by experimentation: biology and chemistry cannot work in any other way. The present inventor has found that concentration ratios are important in compound formulations along with proper ratios of the components, and the present invention optimizes both. The present invention provides a proven innovative, formulation which exemplifies the goal of superior cidal effects while maintaining a low environmental impact thru its outstanding synergy. This is a true synergy. By using this unique approach bacteria require a longer time frame to attempt resistance and bacterial resistant transferase is considerably slow to develop resulting in decreased toxicity to environment and improved effectiveness through the synergistic approach.